1. Field of the Invention
This invention relates to coil lifters and handling devices used for transporting coils of material such as steel, aluminum or the like. More specifically, this invention relates to coil lifters which protect the coil of material.
2. Description of the Prior Art
Coil lifters and handling devices used by many industries generally employ one of two lifting approaches. The approaches vary by the way in which a coil of material is positioned. Certain coils of material do not possess sufficient strength, especially soon after formation or rolling, to be laid on their edges. These coils are positioned, at rest, with the core through the center of the coil running horizontally.
The coil lifters used in transporting coils positioned in this manner typically employ the following approach. The coil lifter is suspended over the coil to be transported. The lifter arms of said coil lifter are moved apart a distance in excess of the overall coil width. The lifter arms are lowered about the coil of material until lifting surfaces at a lower end of each lifter arm are positioned for entry into the circular coil core ends. The lifter arms are moved together to close about the coil of material. Specifically, the lifter arms are moved toward one another until the opposed front wall of each arm contacts with the edges of the coil therebetween. The lifter arms are then raised along the edges of the coil until the lifting surface of each arm contacts with the upper curvature of each coil core surface end. Thereupon, the coil lifter and coil of material can be raised and moved about for transportation of the coil. Exemplary of such coil lifters are U.S. Pat. Nos. 3,002,779; 3,771,666; 3,291,519; 4,641,876; 4,709,953; 4,717,188; 4,784,419 and 4,919,465.
For those coil lifters presently known in the art, there is normally no resultant damage caused by the initial contact of the front wall of each lifter arm with the edges of the coil. As shown in FIG. 1, early coil lifter designs damage the edges 1 of the coil 3 and the coil core surface 5 as the lifter arms raise therealong for the contacting of the lifting surfaces with the upper curvatures of each coil core end. Further, damage to the edges resulted when the coil was subsequently lowered after transportation. Most of the damage to the coil was to the edges as opposed to the coil core surface. Subsequent designs incorporated edge protectors and reduced coil edge damage. See, for example, U.S. Pat. No. 4,641,876. Presently, the coil lifters still damage the coil core and results in lost profit because the damaged portion must be removed from the coil.
Therefore, it is an object of my invention to provide a coil lifter that reduces or eliminates damage to the coil core surface during operation.